It definitely explores the dark side much more (ie: The tagline is 'you don't make it to 500 million friends without making a few enemies'), but there are parts where I found myself laughing out loud. Seriously, Sorkin wrote those parts for Eisenberg and Timberlake. Envisioning some of those lines; it's just too perfect.
It's heartbreaking. You get emotionally involved with these characters, Eduardo especially, and the slow burn pays off so well... I really dug the script, thinking this may be my favorite movie of the year, knowing it'll get snubbed come Oscar season. Sorkin will get a nod but not a win, and Fincher will be overlook as director because of content.